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Electro-optical device and electronic device

a technology of optical devices and electronic devices, applied in the direction of discharge tubes, luminescnet screens, and semiconductor/solid-state device details, etc., can solve the problems of tfts operation serious trouble, el material degradation due to moisture,

Inactive Publication Date: 2004-04-01
SEMICON ENERGY LAB CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to an electro-optical device, particularly an EL display device, which has good operation performance and high reliability. The invention aims to prevent degradation of the EL elements due to moisture, heat, and release of alkaline metals. To achieve this, an insulating film with blocking effects against moisture and alkaline metals is placed in contact with the EL elements or encloses them. The invention also includes various methods for manufacturing the active matrix type EL display device. The technical effects of the invention include improved image quality and reduced manufacturing costs.

Problems solved by technology

Degradation of EL materials due to moisture has been a problem in these EL display devices.
However, the problem that the EL layer has is not limited to moisture.
The EL layer includes alkaline metals such as sodium (Na) in itself, and a serious trouble can be caused to the operation of TFTs when the alkali metals are diffused into the TFTs.
Further, degradation due to storage of heat is also a problem because an EL layer is weak to heat.

Method used

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  • Electro-optical device and electronic device
  • Electro-optical device and electronic device

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embodiment 1

[0109] Embodiment 1

[0110] The embodiments of the present invention are explained using FIGS. 3A to 5C. A method of manufacturing a pixel portion, and TFTs of a driver circuit portion formed in the periphery of the pixel portion, is explained here. Note that in order to simplify the explanation, a CMOS circuit is shown as a basic circuit for the driver circuits.

[0111] First, as shown in FIG. 3A, a base film 301 is formed with a 300 nm thickness on a glass substrate 300. Silicon oxynitride films are laminated as the base film 301 in embodiment 1. It is good to set the nitrogen concentration to between 10 and 25 wt % in the film contacting the glass substrate 300.

[0112] Further, it is effective to form an insulating film, made from the same material as that of the first passivation film 41 shown in FIG. 1, as a portion of the base film 301. A large electric current flows in a current control TFT, heat is easily generated, and therefore it is effective to form the heat radiating layer a...

embodiment 2

[0198] Embodiment 2

[0199] In embodiment 2, an example of a pixel constitution is shown in FIG. 10 which differs from the constitution shown in FIG. 2B.

[0200] The two pixels shown in FIG. 2B are arranged with symmetry around the current supply line in embodiment 2. Namely, as shown in FIG. 10, by making the current supply line 213 common between the two pixels neighboring the current supply line, the number of wirings needed can be reduced. Note that the structure of the TFTs placed inside the pixels may be left as is.

[0201] If this type of constitution is used, then it becomes possible to manufacture a very high precision pixel portion, increasing the image quality.

[0202] Note that the constitution of embodiment 2 can easily be realized in accordance with the manufacturing processes of embodiment 1, and that the explanations of embodiment 1 and of FIG. 1 may be referenced regarding points such as the structure of the TFTs.

embodiment 3

[0203] Embodiment 3

[0204] A case of forming a pixel portion having a structure which differs from that of FIG. 1 is explained using FIG. 11 in embodiment 3. Note that processes up through the formation of the second interlayer insulating film 44 may be performed in accordance with embodiment 1. Furthermore, the structures of the switching TFT 201 and the current control TFT 202, covered by the second interlayer insulating film 44, are the same as those of FIG. 1, and their explanation here is omitted.

[0205] In the case of embodiment 3, a pixel electrode 51, a cathode 52, and an EL layer 53 are formed after forming a contact hole in the second passivation film 45, the second interlayer insulating film 44 and the first passivation film 41. The cathode 52 and the EL layer 53 are formed in succession, without exposure to the atmosphere, by vacuum evaporation in embodiment 3, and at that time a red color emitting EL layer, a green color emitting EL layer, and a blue color emitting layer ...

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Abstract

An object of the present invention is to provide an EL display device, which has a high operating performance and reliability. A third passivation film 45 is disposed under an EL element 203 which comprises a pixel electrode (anode) 46, an EL layer 47 and a cathode 48, to make a structure in which heat generated by the EL element 203 is radiated. Further, the third passivation film 45 prevents alkali metals within the EL element 203 from diffusing into the TFTs side, and prevents moisture and oxygen of the TFTs side from penetrating into the EL element 203. More preferably, heat radiating effect is given to a fourth passivation film 50 to make the EL element 203 to be enclosed by heat radiating layers.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to an electro-optical device, typically an EL (electroluminescence) display device formed by a semiconductor element (an element using a semiconductor thin film) made on a substrate, and to electronic equipment (an electronic device) having the electro-optical device as a display (also referred to as a display portion).[0003] 2. Description of the Related Art[0004] Techniques of forming a TFT on a substrate have been widely progressing in recent years, and developments of applications to an active matrix type display device are advancing. In particular, a TFT using a polysilicon film has a higher electric field effect mobility (also referred to as mobility) than a TFT using a conventional amorous silicon film, and high speed operation is therefore possible. As a result, it becomes possible to perform pixel control, conventionally performed by a driver circuit external to the substrate, by a driver circuit formed on...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02B27/00H05B44/00H01L21/77H01L27/32H01L51/52
CPCH01L27/1214H01L27/322H01L27/3258H01L51/5253H01L51/529H01L51/56H01L29/78621H01L23/3171H01L27/1248H01L2924/0002Y10S428/917H01L2924/00H10K59/38H10K59/124H10K71/00H10K59/8794H10K59/873H10K59/131G02B27/00H10K50/844H10K50/87H10K59/12
Inventor YAMAZAKI, SHUNPEIKOYAMA, JUNYAMAMOTO, KUNITAKAKONUMA, TOSHIMITSU
Owner SEMICON ENERGY LAB CO LTD
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